Joberg, thanks for the correction, I'm re-calculating proportions based on that.
Trying to finish a skeletal test rig of the arm movements - taking a bit longer due to having the flu for the past 2 days. Need to check if the servo's I have are good enough or if I need higher torque._________________If only you could see the things I've seen with your eyes.

Tom, I don't know if you've planed to use light-weight materials for the arm/eye combo? It's a factor for sure, in terms of selecting the right motors.
I know that if you have a stronger motor, you'll add additional weight...You seem to know better in that stuff than me

Sorry for the long delay in updating progress and status. I've made a bit of progress, despite hitting a lot of roadblocks.

The arm extension, along with the "eye" piece flipping up, is actually working now that I upgraded the servos to ones with metal gears and higher torque. Some issues with the raising of the arm - even using aluminum the arm ends up being to heavy for standard servo's. After testing a bunch of DC motors with reduction gearboxes I thought I would have to order a NEMA 17 stepper motor with a planetary gearbox (they have more than enough torque and holding power for the arm but they are fairly expensive). I still think the NEMA stepper would be ideal but I came across a larger DC motor with a bigger gearbox (was used in an industrial soap dispenser) and it seems like it will just fit into the VK.
Screens have definitely been a real pain but I found one for the main screen that I think is nearly perfect: 5.6inch AT056TN52 V3 50Pin LCD panel (it is a 640x480 display with a 4:3 aspect ratio - just like the 80's only an LCD instead of CRT - can find them from Chinese companies). I'm just waiting for the controller board for it (nice thing is that is can utilize a composite NTSC signal. I have smaller TFT/LCD screens (2.8"diagonal - but I plan to use a fresnal lens in front of each one). These have been a real issue though, after many many hours of attempting to use them I still can't get them to display anything.

Sensors have presented some issues but are progressing rather well. The initial pulse/ox sensor I was unable to get working (mainly due to the small size of the surface mount pads). I found a slightly more current sensor, already mounted in a breakout board - MAXREFDES117#. The advantages of this board are that the component is already mounted and it comes with code libraries to speed development. It is a nice small board but the code libraries from Maxim Integrated do not compile - I contacted the company and they are working on it. Looking for a quicker solution I came across a code library made by Spark Electronics and it actually works (YES!).

Eye tracking software seems to work reasonably well (still messing with the software).

Non-contact Infrared temperature sensor - works but not great at any reasonable distance. So, looking at other ways to address this.

Working to improve the Electrodermal Activity sensor (GSR) - works but trying to amplify and filter the signal.

More to come, with pictures (just trying to figure how to post them so they aren't gigantic)._________________If only you could see the things I've seen with your eyes.

Great update...despite the blood, sweat and tears that machine will give you (and I'm not even talking about the headaches ).

I was using a alu tube for the arm (lighter as you well know). The main block for the arm (the one on which the pullies are sitting) is machined aluminium also; hollowed at the bottom as to make sure the tube slides at a 1/4 in that block.

If you look at pictures of the innards, that servo box moving the arm is taking almost the whole length of the machine...for reasons you've discovered. The whole arm + eye combo is fairly heavy
Let's re-cap for people not familiar with that stuff:

Box at the base of the arm (contains servo for moving tube + gear box attached to the eye.
Alu-block with 2 pullies.
Gear box at the end of the tube
Eye piece.

Now, if you take that whole arm in your hand, it doesn't seem that heavy.
True, but one has to consider the length of the extended arm + gear box + eye piece, making it heavy for a normal gear box.

Looking at the machine, back in the '80s, it's a miracle that they could make it work. Nowadays, the electronics are much more smaller and the possibilities are there to make it work...albeit with some challenges, still present at hand, namely the screens.

Finally - some successful test for the VK arm. I thought this would be the easy part but it definitely wasn't.
Servo motors – primarily the motor to extend the arm, needed more torque and metal gears. I thought I solved this when I got some SG-90 servo's from Tower Pro but it turned out I needed a standard size servo. Before that I encountered one new issue with the servo for arm extension – I incorrectly thought that the servo would rotate more than 180 degrees (for some reason I had it in my head that they rotated closer to 360 degrees - oops). Thankfully I was able to fix this by converting the servo motor into a continuous rotation gear motor ( https://learn.adafruit.com/modifying-servos-for-continuous-rotation/overview ). For the final build I will need to add limit switches to mark the endpoints of the travel of the arm.

Next - I'll get the arm raise working! After putting together a test rig for my largest geared motor only to find that it had insufficient torque at lower speeds (controlling with PWM and a L293 H-Bridge). I ended up ordering a NEMA 17 stepper motor with a planetary gearbox (5:1 reduction), the torque ratings look more than sufficient to move the arm._________________If only you could see the things I've seen with your eyes.

The belt that I'm testing with came out of an old VCR.
I thought I'd have the arm raise working by now but I burned out 2 micro-controllers and 2 stepper motor drivers trying to get it going. Normally stepper motors are no issue for me but now I have to wait for some new stepper drivers to come (a few days)._________________If only you could see the things I've seen with your eyes.

LearnByMaking: this is an intriguing project. Challenge enough to make a static replica, I'd imagine, but a working model is something else. Best of luck with the contest. Here's hoping you bring home a "blue ribbon".

Finally have all the motors functioning independently - arm raise, arm extension and eye rotation. Just trying to write some code to actually have one go after the other - think I have it solved but can't try it out until I'm back in town tomorrow. In the hopes of smoother movement I ordered some continuous rotation servos to replace my hacked servos.
In response to Joberg, so far I haven't needed a grove in the rod to prevent rotation (it is something I worry about though) - so far it stays straight as long as the push rod is secured in 2 different spots on the belt. I wasn't sure if you meant a grooved or toothed belt (I may need to switch to a toothed belt but I hope not) the belt I'm testing everything with is an old square rubber belt that attached one fan the motors in a old VCR to the tape spindle.
Additionally, I think I have a mechanism for the moving bellows (I've tested it and it works but need to size it to fit the VK dimensions) the drive is similar to the arm extension but using a stepper motor - I should be able to get video of that up tomorrow (4/4/17)._________________If only you could see the things I've seen with your eyes.

I meant grooved belt...but if you've tested the whole arm-eye combo and didn't see a prob, that could be the end of that grooved belt

I think the bellows are the "easy" part of the prop; they could be attached together (like a link belt) and a push rod going through the 4 bellows could push the top one to make the others move...I know, there's 5 on the machine, but, if my memory serves me well, the bottom one never moves.

Keep up the great work...I know that it's maybe too soon to ask, but what type of material are you gonna use to make the exterior of the prop?

Here's a video of my most recent tests:
https://youtu.be/Fi3bzY4IJtk
(includes arm raise with new stepper motor, "eye rotation" and simple mechanism for bellows).

As Joberg mentioned, the bellows are the simplest of the moving parts - I needed an easy success after a run of failures.

In reply to Joberg - it's never to early to look at materials and it is something that I'm trying to figure out. I'm thinking some type of plastic or resin but I have little experience at something as big as the VK. I have 3D printed parts up to 5"x5"x2" and filled (with Bondo, etc) sanded and then used for making simple molds for resin casting. Any suggestions would be great (not scared to try things I haven't done before).

Another youtube video (from tonight) where I got to talk a little about this build (I'm at 13:02 minute mark):
https://www.youtube.com/watch?v=eYMHIj7Ij0A_________________If only you could see the things I've seen with your eyes.

Good stuff...I know, that you're trying to move your servo with pieces of foam core and such attached to it. I know that weight will be a factor into moving those parts in a smooth way.

Good progress on the bellows...but your servo mechanism is too tall to fit into that V.K. You'll have to find a way to do the same thing but with a horizontal mechanism.

As for material to build the prop itself: yes, the eye could be 3-D printed as well as the hollow part near the eye (containing the servo moving the eye).

The original prop had a vacu-form top (as you can see on the pics) and probably a vacu-form bottom as well. Walls are made out of resin/plastic or even wood clad in some kind of plastic...you never know.

Bellows are also vacu-formed; you only need to build one buck for those...I learned that they will fold onto each other just fine